Talk:Radical of a ring

What does the imprint z mean
What does the imprint z mean on a ring 2600:6C55:4600:DBEA:DC91:2488:CE92:6D83 (talk) 02:59, 4 December 2021 (UTC)

What does not-good mean?
The term not-good is used in the first sentence, but is not defined, is not a link and not mentioned again. 2A02:8071:3E81:1E20:B0DC:23D5:D783:FEFF (talk) 09:38, 10 June 2023 (UTC)